Valve assembly

ABSTRACT

A hydraulic valve includes a closure member, wherein the closure member is actuable toward an opening sealed thereby in the valve, but is unconstrained to move with respect to the opening when the valve is in a closed position. In an aspect, the closure may be a thin disk, in the shape of a flat washer, which is located between the valve and piston of a hydraulic damper, and when the valve is positioned away from an opening through the piston by virtue of differential pressure across the valve in a dampening r rebound stroke, the disk is free to rotate, move from side to side, and move away from and toward the piston. By employing such a disk, sympathetic vibrations in the damper created during compression events are eliminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and claims priority of U.S.provisional patent application Ser. No. 61/937,937, filed on Feb. 10,2014, entitled “VALVE ASSEMBLY” by Bryan Wesley Anderson, assigned tothe assignee of the present application, and is hereby incorporated byreference in its entirety herein.

BACKGROUND Field of the Invention

The present invention relates to the field of hydraulic valves, whereina hydraulic valve element is configured to enable or prevent fluid flowtherepast or therethrough. More particularly, the invention relates tohydraulic valve(s), with a valve seat member having a valve seat thereinadjacent to an opening, the flow through which is controlled by thehydraulic valve, and a valve element member that includes structuretherein that is configured to sit against the valve seat and therebyopen and close off fluid flow through the opening. The valve seat memberand the valve element member are provided in a movable relationship toone another.

Background

Hydraulic valves commonly include a valve seat which may surround anopening, the flow through which is controlled by the valve, and aseparate closing structure, which may be located on a second elementwhich is moveable with respect to the valve seat to open and close offfluid access to the opening. The second element of the valve is commonlybiased with respect to the first element, either to maintain separationthereof from the first element during normal operation, or to maintainthe valve seat and element in contact with one another by biasing theclosing structure to press against the valve seat and thereby close offthe opening to fluid flow therethrough. The bias may be maintained bymechanical mechanisms such as springs, electrical mechanisms such asactuators, or simply by fluid pressure, when changes in fluid pressureon one or the other side of the valve opening can create a net force toovercome a normal operational biasing force and cause relative movementbetween the two valve elements.

Hydraulic valves are used in many applications, including hydraulicdamping systems for vehicles, such as for two wheeled vehicles such asbicycles and motorcycles and three wheeled and larger vehicles, such asautomobiles and trucks. In these damping systems, restricted flowthrough the valve opening may be used to create a damping force in thevehicle suspension, thereby reducing the velocity at which the vehiclebody and a tire or other terrain encountering element move with respectto one another when the vehicle moves over an obstacle or encounters arecess such as a depression in pavement.

During high force events, where the vehicle suspension components wouldotherwise move rapidly with respect to one another, the flow velocityand the rate of fluid flow through the openings can reach a maximumattainable value. Likewise, during lower energy events, when open, theopenings may provide minimal restriction to fluid flowing therethrough.Thus, the valve needs to be designed to meet a broad range of flowquantities and flow velocities to properly dampen the relative motion ofthe vehicle frame and suspension.

One issue encountered in hydraulic valves is that at certain fluid flowspeeds or flow quantities therethrough, the flow through the opening, orthrough a flow path adjacent to or within the valve leading to or fromthe opening, may create a chirp or squeal sound, or deeper clunk soundaccompanied by a physical sensation. While not wishing to be bound bytheory, these effects are believed to be caused by a driven oscillationof the valve elements resulting in undesirable seating characteristics,such as the closing element of the valve oscillating adjacent to or onthe seat, or not closing smoothly as a result of the oscillation suchthat an excess pressure is required to overcome the oscillation and ahard impact of the closing element against the valve seat occurs. Thechirp, squeal or clunk sound, and any physical manifestation thereof,can cause users of the vehicle to believe the damper has failed, causingreturn of the vehicle for service. Further, the initiation of thesevalve sounds and oscillations vary depending on the properties of thehydraulic fluid passing through the valve, such as viscosity, whichchanges as a result of changes in temperature of the fluid and/or thequantity of air or gas entrained in the fluid.

SUMMARY

A valve assembly is provided, that includes: a first member having atleast one opening therethrough and is controlled by the valve assembly,wherein a valve seat is located at or adjacent to an end of the opening;a second member actuable toward and away from the valve seat; and a thinmember located intermediate of the valve and the end of the opening,which is free, within constrained limits, to move with respect to boththe first and second members. When the second elements move in thedirection of the first element, the thin member is positioned againstthe end of the opening to seal the opening from fluid flow therethrough.

The first and the second members and the thin member may be annularstructures, such that a bolt or other connector may pass through anaperture in the centers thereof, and thus secure the elements together.The thin member has a thickness which is less than one-half the distancethat the second member may retract away from the first member. Thethickness is more preferably a thickness in the range of 15 to 40percent of the retraction distance; the retraction distance being themaximum distance between the first and the second member, not includingthe thin member.

The position of the first and second members relative to one another maybe enabled solely by hydraulic fluid pressure on opposed sides of thevalve, or additional mechanical bias, such as a mechanical spring in theform of a coil spring or Belleville washer, or an electromechanicalbias, such as provided by an actuator, or a magneto mechanicalmechanism, may be employed, in addition to the difference in hydraulicfluid pressure to either side of the valve assembly, to effect both thedifference in pressure at which the valve opens, as well as the extent(size) of the opening.

Where the first and the second members and the thin member are annularstructures, the hydraulic fluid flowing from the higher pressure to thelower pressure side of the valve will leave the valve element in an atleast partially radial direction. This may be radially outwardly, orradially inwardly, depending on the valve layout.

The valve structure may be employed as the piston assembly in ahydraulic damper, such as that used to dampen impact and rebound fromimpact events in a vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a partial sectional schematic view of a hydraulic damper,according to an embodiment.

FIG. 2 depicts a sectional view of a piston of a hydraulic damper ofFIG. 1 at section 2-2 of FIG. 4, in accordance with an embodiment.

FIG. 3 depicts an additional sectional view of a piston of a hydraulicdamper of FIG. 1 at section 3-3 of FIG. 4, in accordance with anembodiment.

FIG. 4 depicts a plan view of the top of the piston of the damper ofFIG. 1, with the connecting bolt and upper shims removed for clarity, inaccordance with an embodiment.

FIG. 5 depicts an exploded view of a part of the piston of FIGS. 2 and3, in accordance with an embodiment.

FIG. 6 depicts an enlarged partial view of the piston of FIGS. 2 and 3in the closed position, in accordance with an embodiment.

FIG. 7 depicts an enlarged partial view of the piston of FIGS. 2 and 3in the open position, in accordance with an embodiment.

FIG. 8 depicts an enlarged view of the closure in position to seal apassage of the piston of FIGS. 2 and 3, in accordance with anembodiment.

FIG. 9 depicts an enlarged view of an additional passage and shim valvein an open position of the piston of FIGS. 2 and 3, in accordance withan embodiment.

FIG. 10 depicts a sectional view of an alternative embodiment of thepiston shown in FIGS. 2 and 3, wherein a Belleville washer is employedto add additional closing force of the passage through the piston, inaccordance with an embodiment.

FIG. 11 depicts a sectional view of an alternative embodiment of thepiston shown in FIGS. 2 and 3, wherein a coil spring is employed to addadditional closing force of the passage through the piston, inaccordance with an embodiment.

The drawings referred to in this description should be understood as notbeing drawn to scale except if specifically noted.

BRIEF DESCRIPTION

Reference will now be made in detail to embodiments of the presenttechnology, examples of which are illustrated in the accompanyingdrawings. While the technology will be described in conjunction withvarious embodiment(s), it will be understood that they are not intendedto limit the present technology to these embodiments. On the contrary,the present technology is applicable to alternative embodiments,modifications and equivalents, which may be included within the spiritand scope of the invention as defined by the appended claims.

Furthermore, in the following description of embodiments, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present technology. However, the present technologymay be practiced without these specific details. In other instances,well known methods, procedures, and components have not been describedin detail as not to unnecessarily obscure aspects of the presentdisclosure.

The following discussion will first briefly describe variousembodiments. The discussion then turns to a description of the FIGS.1-11 and embodiments shown therein.

Embodiments describe a hydraulic valve in which a first element thereofincludes a passage extending therethrough and opening into a facethereof, and a second element that is configured to move against or awayfrom the opening to close or open the valve to fluid flow. When in theopen position, the fluid flows from the opening and through a gapbetween the first and second elements to the lower pressure side of thevalve. Thus, the spacing between the second element and the opening willaffect the resistance to flow of the fluid and thus the flow ratethrough the valve. It has been found that in such a valve structure, thevalve can emit sounds such as a chirping, squealing or clunking sound,and in some cases, cause the second element to oscillate at or near theopening when the valve should be in an open position or closed position.When the valve is used as the piston assembly in a suspension to vehicledamping system, this can lead to jerking or vibration of the vehicleframe as the valve rapidly opens and closes during a compression event.Embodiments herein locate a thin spacer element of a size capable ofblocking the opening when pressed there against by the second member,but also not physical physically rigidly connected to any other valvestructure, the noises are ameliorated to the point of not beingnoticeable, or are completely eliminated.

Referring first to FIGS. 1 and 2, there is shown, in accordance with anembodiment, a depiction of a damper 10, having a damper housing 12 whichis internally separated into a compression volume 14 and a reboundvolume 16 by a piston assembly 18 movably disposed therein, the motionof which changes the relative sizes of the compression volume 14 and therebound volume 16. The damper housing 12 is filled with hydraulic fluidthrough a fill port, not shown. The damper housing 12 also includes afirst mount 20 on the exterior of a first end 22 thereof, which includesa bushed aperture 24 through which the damper 10 may be connected to thebody or to the suspension of the vehicle. The second end of the cylinder26 includes a sealing plug 28 extending therein and secured thereto bymating threads 30, 32 on the exterior of the sealing plug 28 and theinterior of the damper housing 12 at the second end of the cylinder 26thereof. The inwardly facing end of the sealing plug 28 includes alanding face 34 thereon, which limits the outward travel of the pistonassembly 18 from the damper housing 12, having a circumferential recess36 extending therein into which a compliant member, such as an o-ring38, may be received. The sealing plug 28 also includes a sealed bore 40extending therethrough, through which a push rod 50 extends. A sealgroove 42 is provided inwardly of the sealed bore 40, having a seal 44therein which seals against the outer circumference of the rod 50. Asecond bore 46, and a clearance opening 48, surround the push rod 50 asit exits and enters the sealing plug 28. A wiper or other generallyelastic component, not shown, may be located in the second bore 46 toprevent contamination from reaching the seal 44/push rod 50 interface.

The push rod 50 is secured, at a first end 52 thereof, to the side ofthe piston assembly 18 facing the rebound volume, and extends therefromthrough the sealed bore 40 of the sealing plug 28, where it terminatesin second mount 54, which includes the bushed hole 56 therethrough. Thesecond mount 54 secures the damper 10 to the other of the body andsuspension portions of a vehicle.

In use, the damper 10 acts to dampen forces acting on the exterior ofthe push rod 50, or on the first mount 20 on the damper housing 12,tending to depress the push rod 50 into the damper housing 12 during acompression event (arrow I), as well as forces of retraction tending toextend the push rod 50 outwardly of the damper housing 12 during arebound event (arrow O). This occurs, at least in part, by the action ofthe piston assembly 18 moving through the hydraulic fluid in the damperhousing 12. Because hydraulic fluid is incompressible or substantiallyincompressible over the range of forces that are imposed thereon in thedamper, hydraulic fluid on one side of the piston assembly 18 must moveout of the volume it occupies if the piston assembly 18 is to move inthe direction of that volume, and move into the volume where the pistonassembly 18 is moving away from and thus enlarging that volume must besupplemented with additional hydraulic fluid, or the piston assembly 18cannot move. In the embodiment shown herein, this is accomplished byselectively flowing or restricting (sealing off) openings which extendthrough the piston assembly 18 between the compression volume 14 and therebound volume 16.

Referring now to FIGS. 2 and 4, details of piston assembly 18 are shown,in accordance with an embodiment. The piston assembly 18 has a similarstructure, but for the improvement in noise elimination disclosedherein, as that shown and described in U.S. Pat. No. 6,978,872, which isincorporated herein by reference. FIGS. 2 and 3 are cutaway views alonglines 2-2 and 3-3 of the piston assembly 18 of FIG. 4, wherein portionsof the piston assembly 18 securing the piston assembly 18 together wereremoved for clarity. In both FIGS. 2 and 3, the arcuate passages 68 areshown in the closed position. The open position of the arcuate passages68 is shown in FIG. 7. The piston assembly 18 includes a piston 60, aguide element 62 in abutting engagement with the underside surface 64 ofthe piston 60, and a sliding valve 66 selectively moveable to bepositioned against, or spaced from, the underside surface 64 of thepiston 60, and guided in an axial direction by surfaces of the guideelement 62.

Referring now to FIG. 2, the piston 60 includes a plurality of arcuatepassages 68 extending therethrough, (3 as shown in FIG. 4), whichprovide an unobstructed flow path entry thereinto from the compressionvolume 14 side of the piston assembly 18, but are selectively closableand openable at the rebound volume 16 side thereof. The opening andclosing of the passages 68 to the rebound volume 16 is controlled by theposition of the sliding valve 66, and a thin annular disk 146 vis a visthe underside surface 64 of the piston 60 at the location of the arcuatepassages 68.

Referring particularly now to FIGS. 6 and 7, sliding valve 66 isconfigured to move freely in the axial direction of the damper housing12 on an outer circumferential surface 70 of the guide element 62, andbe sealingly engaged with an inner circumferential surface 71 thereof,in accordance with an embodiment. Thus, the sliding valve 66 is agenerally right circular element (as seen in the exploded view of thepiston assembly 18 of FIG. 5). The inner portion of the body of thesliding valve 66 extends from a circumferential annular face 72extending annularly around the perimeter of the sliding valve 66 on oneside thereof, and includes a circumferential recess 74 extendinginwardly of the body and bounded by an outer wall 76, a base 78, and anintermediate wall 80 extending from the wall generally parallel to, andspaced from, outer wall 76. Extending inwardly from the end ofintermediate wall 80 distal from the base 787 is a ledge 82, whichterminates at an inner circumferential surface 71 of the guide element62. On the opposed side of the sliding valve 66, a lower wall surface 90includes spaced projections 91 extending therefrom, and a countersinkregion having tapered circumferential wall 92 extending inwardly of thebody of the sliding valve 66 from the lower wall surface 90, and arecessed face 94 extending circumferentially around an inner bore 110 ofthe sliding valve 66. A lower inner wall 98 extends upwardly from therecessed face 94, such that a gap in which the seal bore 98 is formed,extends between the lower terminus of the inner wall 84 and the upperterminus of the lower inner wall 86, and an o ring 102 is receivedtherein to seal the inner bore 100 of the sliding valve 66 against theinner circumferential surface 71 of the guide element 62.

Referring still to FIGS. 6 and 7, guide element 62 includes an innerbore 110, through which a bolt shank 140 extends (FIG. 2), and extendingtherefrom adjacent to and contacting the underside surface 64 of thepiston 60, an outwardly projecting face 112 terminating in thedownwardly projecting outer circumferential surface 70. The outercircumferential surface 70 of the guide element 62 includes a sealrecess 118 to which an o-ring seal 120 is provided to seal the outercircumferential portion at the outer circumferential surface 70 of theguide element 62 to the outer wall 76 of the sliding valve 66.Additionally, at the lower end of the guide element 62, a recess 122 isformed and is bounded by inner circumferential surface 71, base 124 andwall 126, and from the lowermost end of wall 126 extends a lower annularface 116 terminating at the outer circumferential surface 70. Thus, theinterfaces of adjacent surfaces of the guide and the valve are sealed attwo different locations. A thin annular disk 146 is located between thesliding valve 66 and the opening of the arcuate passage 68 through theunderside surface 64 of the piston 60. The design features of the guideelement 62 and sliding valve 66 form mating circumferential recesses andprotrusions, in which o-ring seals are provided, such that axialmovement of the sliding valve 66 with respect to the guide element 62 ispossible, but radial and rotational movement is significantlyconstrained.

Referring back to FIGS. 2 and 3, the piston assembly 18, including thepiston 60, guide element 62, thin annular disk 146 and the sliding valve66, are held together by the bolt 150, having a bolt head 152 extendingradially outwardly around the circumference of the bolt head 152 in ahexagonal profile as shown in FIG. 1, the bolt shank 140 extendingtherefrom and through the piston 60, guide element 62, thin annular disk146 and sliding valve 66, and extending therefrom and terminating in athreaded end 154. A limit plate 158 is received around the bolt shank140 adjacent to the threaded end 154 in the end of the push rod 50, tosecure the piston assembly 18 together.

Two additional elements are also located in the piston assembly 18, bothof which extend circumferentially around, and are held in place therein,by the bolt shank 140 extending through the limit plate 158 and threadedinto the push rod 50. These include a plurality of valve shims 164,disposed between the underside 162 of the bolt head 152 of the boltshank 140 on the side of the piston 60 opposite to the position of thesliding valve 66, and which serve as bendable valve shims forselectively allowing fluid to pass through a plurality of secondapertures 160 extending through the piston 60. On the valve side of thepiston assembly 18, between the limit plate 158 and the lowermostextending portion of guide element 62 are one or more spacers 166.

Referring now to FIGS. 5, 6, and 7, details of the closure element forthe valve assembly of the piston assembly 18 is shown, in accordancewith an embodiment. In this embodiment, the thin annular disk 146,which, when provided, results in amelioration or elimination ofchirping, squealing or the chunk sound during operation of the valve toopen and close the arcuate passages 68, is shown. The thin annular disk146, having an inner circumference 142 of a diameter “id”, and an outercircumference 144 of a diameter “od” is shown (best seen in FIGS. 5, 6,and 7) disposed between the circumferential annular face 72 of thesliding valve 66 and the underside surface 64 of the piston 60 such thatwhen the sliding valve 66 is in the closed position, as shown in FIGS. 2and 6, the thin annular disk 146 covers the arcuate passages 68 andthereby closes off flow through the arcuate passages 68 between thecompression volume 14 and the rebound volume 16. When the sliding valve66 is in the open position with respect to the piston 60, as shown inFIGS. 3 and 7, the thin annular disk may retract away from the arcuatepassages 68, allowing fluid flow therethrough. As is also shown in FIG.8, the thin annular disk 146 has a thickness I. The outer diameter “od”of the thin annular disk 146 is greater than the outer diameter of thesliding valve 66, and the inner diameter of the thin annular disk 146 isslightly larger than the outer diameter of the guide element 62 at theouter circumferential surface 70 thereof.

Referring particularly now to FIGS. 6 and 7, when the sliding valve 66is positioned to position the thin annular disk 146 to close off thearcuate openings 68, a gap “s” exists between the recessed face 94 andthe furthest extension of the spacers 166 from the limit plate 158.When, as shown in FIG. 7, the sliding valve 66 is in the fully retractedposition from the underside surface 64 of the piston 60, the recessedface 94 thereof contacts the furthest extension of spacers 166 from thelimit plate 158, which occurs when the sliding valve 66 has moved awayfrom the piston 60 by the distance s. In this position, fluid from thecompression volume 14 moves through the arcuate passages 68 and flowsradially outwardly from the gap between the annular thin plate 146 andthe underside surface 64 of the piston 60 and then into the main volumeof the rebound volume 16 as shown by arrow f of FIG. 7.

The thin annular plate 146 is not rigidly secured to any element of thepiston assembly 18. Thus, in the valve closed position of FIGS. 2, 3,and 6, the thin annular plate 146 is constrained against movement onlyby the force of the sliding valve 66 against the piston 60, which is afunction of the pressure in the arcuate passages 68 multiplied by thecross sectional area of those arcuate passages 68, relative to thepressure in the rebound volume 16 multiplied by the effective area ofthe sliding valve 66 which is exposed to the rebound volume (therelative area of which is larger than that of the arcuate passages 68),and by the guide element 62. When the pressure in the arcuate passages68 multiplied by the cross sectional area of those arcuate passages 68,exceeds the pressure in the rebound volume multiplied by the effectivearea of the valve which is exposed to the rebound volume, the net forceat the surface of the thin annular disk 146 exposed to the arcuatepassages 68 will be in the direction of the rebound volume. Once anyadhesive tension of the disk to the underside surface 64 of the piston60 and the friction of the o-ring seals 120 and 102 between the guideelement 62 of the sliding valve 66 are overcome, the sliding valve 66will move away from the underside surface 64 of the piston 60, andhydraulic fluid will flow from the compression volume 14 to the reboundvolume 16 sides of the piston assembly 18 through arcuate passages 68.However, the thin annular disk 146 is now free to move radially to thelimit of the difference between the “id” thereof and the circumferenceof the outer circumferential surface 70 of the guide element 62, as wellas rotationally about its circumference, and axially toward and awayfrom the circumferential annular face 72 and the opening of the arcuatepassage 68 through the underside surface 64. By employing the thinannular disk 146, it has been found that in comparison to a pistonassembly having the same relative sizes and shapes of the elements, butwhich does not employ the thin annular disk 146, the undesirable noisedoes not occur, wherein when a damper without the thin annular disk 146is employed, the undesirable noise occurs. This has been verified in apiston assembly having the structure of FIGS. 2 to 7 hereof, where theflow leaves the arcuate passages 68 in a radial outward flow direction,and in a similar piston assembly structure, but the flow is radiallyinward across the face of the thin annular disk 146 from the high to thelow pressure side of the piston assembly. Additionally, employing a thinannular plate 146 which has a thickness I which is 15% to 40% of thespacing “s”, the noise emanating from the valve as fluid flowstherethrough is eliminated or is non-detectable.

The piston assembly 18 of the embodiment is also configured toselectively open and close a flow path from the rebound to thecompression sides of the piston assembly 18, when the rebound volume 16pressure is greater than that in the compression volume 14. Referringnow to FIGS. 3 and 4, operation of the piston assembly 18 to enablehydraulic fluid flow from the rebound volume 16 to the compressionvolume 14 will be described. As discussed infra, a plurality of secondapertures 160 extend through the piston 60. The plurality of valve shims164 are positioned over the compression side face 170 of the piston 60.The plurality of valve shims 164 are positioned over the compressionside face 170 of the piston 60, and extend outwardly from the centerthereof so as to overlap the location of the opening through thecompression side face 170, but not so far as to block or overlay thearcuate passages 68. On the rebound volume side of the piston 60, aplurality of recesses equal in number to the number of the plurality ofsecond apertures 160 extend inwardly of the underside surface 64 of thepiston 60 where the plurality of second apertures 160 open therethrough.These recesses (only one shown) extend radially outwardly to the outercircumference of the piston 60, providing a gap between the thin annulardisk 146 and the plurality of second apertures 160 even when the thinannular disk 146 is pressed against the underside surface 64 of thepiston 60. Thus, the radial opening between the thin annular disk 146and the arcuate opening 68 is present and maintained.

The piston 60 is configured to slide within the damper housing 12 whilepreventing fluid leakage between the piston 60 and the interior wall ofthe damper housing 12. The piston 60 is thus provided with an annularrecess 184, within which a sliding seal ring 182 made of a plastic suchas Delran is received, and a seal ring is received within a furtherrecess to seal and push against the seal ring 182.

Operation of the damper 10 will now be described. In a compressionstroke, where forces acting on the push rod 50 or the damper housing 12tend to move the push rod 50 in the direction I with respect to thedamper housing 12, movement of the piston in the direction of the firstend 22 of the damper housing 12 will result in higher hydraulic fluidpressure in the compression volume 14 than in the rebound volume 16,causing the thin annular disk 146 and the sliding valve 66 to move awayfrom the underside surface 64 of the piston 60 in an axial directiongenerally parallel to the longitudinal axis of the push rod 50, guidedby the complementary surfaces of the guide element 62 and the slidingvalve 66, thereby allowing the thin annular disk 146 to move off of theunderside surface 64 of the piston 60 and causing the arcuate passages68 to be in open communication with the compression volume 14 and therebound volume 16. As a result, the piston 60 can move within the damperhousing 12 in the direction of the first end 22 thereof, under thedampening effect of the hydraulic fluid being restricted by flowingthrough the arcuate passages 68. Also, the pressure in the compressionchamber that is higher than the rebound chamber ensures a hydraulicfluid force acting in the direction “O” on the plurality of valve shims164 to help maintain them in a closed condition.

When the full compression stroke is completed, and the forces acting onthe push rod 50 and/or the damper housing 12 tend to move the push rod50 in the direction “O” relative to the damper housing 12, the pistonassembly 18 moves away from the first end 22 of the damper housing 12and thereby in a direction to reduce the size of the rebound volume 16.As a result, the pressure in the rebound volume 16 will exceed that inthe compression chamber, causing the sliding valve 66 and thus the thinannular disk 146 to move against the underside surface 64 of the piston60 and seal off access of hydraulic fluid in the rebound volume 16 tothe arcuate passages 68. As the pressure in the rebound chamber rises,it will reach a level higher than that in the compression chamberwhereby the hydraulic pressure in the plurality of second apertures 160is sufficient to cause the plurality of valve shims 164 to bend as shownin FIG. 9, and thus allow hydraulic fluid to follow path f from theplurality of second apertures 160 into the compression chamber. Thus, ashydraulic fluid leaves the chamber having the rebound volume 16 andenters the chamber having the compression volume 14 through therestricted plurality of second apertures 160, a dampened rebound effectis achieved.

Although the embodiment of a valve assembly described herein in relationto a piston assembly of a damper includes a relatively free floatingsliding valve 66 element, i.e., one biased on or off the opening bydifferential fluid pressure only, the sliding valve 66, and may beotherwise additionally or solely biased. For example, as shown in FIG.10, the sliding valve 66 is additionally biased by a Belleville washer200 disposed between the limit plate 158 and the underside of thesliding valve 66 facing the limit plate 158. To maintain the samedistance between the uppermost surface of the one or more spacers 166and the recessed face 94 of the sliding valve 66, additional spacers areadded to extend the height or span thereof from the limit plate 158. TheBelleville washer 200 is shown in FIG. 10 in an extended but stillcompressed position, wherein force is imparted by the Belleville washer200 against the underside of the sliding valve 66, urging the slidingvalve 66, and thus the thin annular disk 146, in a position to seal theopening of the arcuate passages 68 through the underside surface 64 ofthe piston 60. To move the thin annular disk 146 away from the openingsof the arcuate passages 68 in the underside surface 64 of the piston 60,the pressure in the arcuate passages 68 multiplied by the crosssectional area of those arcuate passages 68, must exceed the pressure inthe rebound volume 16 multiplied by the effective area of the valvewhich is exposed to the rebound volume 16 plus the force of theBelleville spring 200 acting to urge the sliding valve 66 in thedirection of the piston 60.

In FIG. 11, in accordance with an embodiment, a coil spring 210 is shownin contrast to a Belleville washer 200 as a means of additionallybiasing the sliding valve 66, and thus the thin annular disk 146 againstthe opening of the arcuate passages 68 in the underside face 64 of thepiston 60. To maintain the same distance between the uppermost surfaceof the one or more spacers 166 and the recessed face 94 of the slidingvalve 66, additional spacers are added to extend the height or spanthereof from the limit plate. The coil spring 210 is shown in FIG. 11 inan extended but still compressed position, wherein force is imparted bythe coil spring 210 against the underside of the sliding valve 66,urging the sliding valve 66, and thus the thin annular disk 146, in aposition to seal the opening of the arcuate passages 68 through theunderside face 64 of the piston 60. To move the thin annular disk 146away from the openings of the arcuate passages 68 in the undersidesurface 64 of the piston 60, the pressure in the arcuate passages 68,multiplied by the cross sectional area of those arcuate passages 68,must exceed the pressure in the rebound volume 16 multiplied by theeffective area of the valve which is exposed to the rebound volume 14plus the force of the coil spring 210 acting to urge the sliding valve66 in the direction of the piston 60.

Although the valve assembly herein has been described in terms ofincorporation thereof into a damping piston of a damper, the valveassembly using a thin annular disk as a closure member as describedherein is applicable to a stationary hydraulic valve where a valveelement moves away from the valved opening in a spaced relationship.Likewise, although a thin annular disk is described herein as effectiveto eliminate noise emanating from a hydraulic valve, the noise reducingor eliminating element may take on other forms. For example, instead ofa right circular annular plate, the thin element may be contoured, inprofile, to fit only over the openings, as long as some type ofalignment mechanism is provided to allow the disk freedom of movement inthe radial, axial and rotational directions, but also realign theelement when closure of the openings therewith is required. Likewise, aninner ring having extensions or petals extending therefrom, which isfree to move but realigned during valve closure, may be employed.Further, the shape of the closure member inner opening need not becircular, but may include flats thereon, or other internal features, solong as freedom of the closure element to move is not unduly restricted.Additionally, the dimensions such as thickness, shape, diameters, etc.,the noise reducing or eliminating element can be readily determined byone skilled in the art by simple trial and error. The damper elements,but for the seals, may be made from metals such as steel, or fromnon-metallic materials wherein sufficient wear resistance of thematerial from fluid flowing through the openings and rubbing of parts,may be used for the damper and valve components.

It should be noted that any of the features disclosed herein may beuseful alone or in any suitable combination. While the foregoing isdirected to embodiments of the present invention, other and furtherembodiments of the invention may be implemented without departing fromthe scope of the invention, and the scope thereof is determined by theclaims that follow.

What is claimed is:
 1. A valve body configured to be positioned foropening and closing of a fluid passage therethrough, said valve bodycomprising: a first element having at least one fluid passage extendingtherethrough and having an opening at a first surface thereof; a slidingvalve moveable with respect to said opening at said first surface ofsaid first element, said sliding valve constrained to move away from ortoward said first element, said sliding valve configured to slide alonga guide element, said guide element having an outer diameter; and aclosure member having a thickness and positioned between said firstelement and said sliding valve, said closure member said closure membernot physically rigidly connected to either said first element or saidsliding valve, the entirety of said closure member not constrained tomove away from or toward said first element when said sliding valve ispositioned away from said first element by a distance greater than saidthickness of said closure member, said valve body having a positionwherein said closure member is not contacted by a biasing feature, saidclosure member extends around said guide element and comprises an innerdiameter greater than said outer diameter of said guide element, saidclosure member free to move radially about a limit of a differencebetween said inner diameter of said closure member and said outerdiameter of said guide element, said closure member eliminating noiseemanating from said valve body.
 2. The valve body of claim 1, wherein,when said sliding valve is fully biased toward said first element, saidclosure member is held therebetween and constrained against movementaway from or toward said first element.
 3. The valve body of claim 1,further comprising: said guide element and said sliding valve comprisecomplementary surfaces which constrain said sliding valve to move onlyaway from or toward said first element.
 4. The valve body of claim 1,wherein said thickness of said closure member is between 15 and 40percent of a maximum distance that said sliding valve can move from itsclosest to its furthest position from said first element.
 5. The valvebody of claim 1, wherein said first element comprises: a second surfacethrough which a fluid passage extends, and a position of said slidingvalve with respect to said first element is a function of a differencein fluid pressure at a first fluid surface and a second fluid surface ofsaid first element.
 6. The valve body of claim 5, further comprising: anadditional flow passage extending from said first surface to said secondsurface thereof, said additional flow passage being controlled by asecond valve.
 7. The valve body of claim 6, wherein said second valvecomprises: a shim valve.
 8. The valve body of claim 1, wherein, whensaid sliding valve is spaced from a first fluid surface of said firstelement, said closure member is free to move between said sliding valveand a first face of said first element.
 9. The valve body of claim 1,wherein said first element, said sliding valve and said closure memberare positioned on an end of a push rod and within a housing of ahydraulic damper.
 10. The valve body of claim 1, further comprising: amechanical biasing element configured to urge said sliding valve in adirection of said first element.
 11. A piston assembly for a hydraulicdamper, said piston assembly connected to an end of a push rod andhaving a longitudinal axis and extending outwardly of a damper housing,said piston assembly comprising: a piston received in said damperhousing and sealed, around its circumference, to an inner wall of saiddamper housing and bisecting said hydraulic damper into a compressionvolume and a rebound volume, and comprising: at least one flow passageextending therethrough, which when in an open position, allows fluidcommunication between said compression volume and said rebound volume; avalve coupled to said piston, said valve being moveable in a directiongenerally parallel to a longitudinal axis of said push rod away from,and toward, said piston and constrained from moving in other directions;a guide element disposed in contact with said piston; and a closuremember disposed between said piston and said valve, said closure membernot physically rigidly connected to either said piston or said valve,and which, when said valve is located adjacent to said piston, isconstrained against movement and, when said valve is spaced from saidpiston, the entirety of said closure member is able to move in adirection generally parallel to said longitudinal axis of said push rod,in a rotational direction around said push rod, and radially withrespect to said push rod, said piston assembly having a position whereinsaid closure member is not contacted by a biasing feature, said guideelement comprises an outer diameter, and said closure member comprisesan inner diameter larger than said outer diameter of said guide element,said closure member surrounding said outer diameter of said guideelement, said closure member free to move radially about a limit of adifference between said inner diameter of said closure member and saidouter diameter of said guide element, said closure member eliminatingnoise emanating from said hydraulic damper.
 12. The piston assembly ofclaim 11, further comprising: said guide element and said valvecomprising complementary features.
 13. The piston assembly of claim 12,wherein said complementary features restrict said movement of said valveto a direction generally parallel to said longitudinal axis of said pushrod.
 14. A method of reducing sympathetic vibration in a piston in ahydraulic damper, comprising: providing said piston separating acompression volume and a rebound volume of said hydraulic damper andhaving at least one passage therethrough selectively communicablebetween said compression volume and said rebound volume; providing avalve, positioned adjacent to said piston, and moveable in a directiontoward and away from said valve but significantly constrained againstmovement in other directions; providing a guide element adjacent to saidvalve; providing complementary surfaces in said valve and said guideelement, such that said guide element limits a motion of said valve tosaid direction that is toward and away from said piston; and providing aclosure member therebetween, said closure member not physically rigidlyconnected to either said piston or said valve, the entirety of saidclosure member free to move toward and away from said piston when saidvalve is spaced away from said piston, and, when said valve is in aposition closest to said piston, said closure member seals off said atleast one passage and is constrained against motion with respect to saidpiston, said valve having a position wherein said closure member is notcontacted by a biasing feature, said guide element comprises an outerdiameter, and said closure member comprises an inner diameter largerthan said outer diameter of said guide element, said closure membersurrounding said outer diameter of said guide element, said closuremember free to move radially about a limit of a difference between saidinner diameter of said closure member and said outer diameter of saidguide element, said closure member eliminating noise emanating from saidhydraulic damper.
 15. The method of claim 14, wherein said closuremember is an annular disk.
 16. The method of claim 15, wherein athickness of said annular disk is between 15 and 40 percent of a fulltravel distance of said valve from a position closest to said piston toa position furthest from said piston.
 17. A fluid valve, comprising: abody having an opening extending therethrough; a valve member moveablebetween a first position adjacent to said opening and a second positionspaced from said opening, said valve configured to slide along a guideelement, said guide element having an outer diameter; and a closuremember disposed between said body and said valve member, said closuremember not physically rigidly connected to either said body or saidvalve member, said closure member positioned to seal said openingagainst fluid flow therethrough when said valve member is in said firstposition, the entirety of said closure member free to move in a gapbetween said opening and said valve member when said valve member is insaid second position, said fluid valve body having a position whereinsaid closure member is not contacted by a biasing feature, said guideelement comprises said outer diameter, and said closure member comprisesan inner diameter larger than said outer diameter of said guide element,said closure member surrounding said outer diameter of said guideelement, said closure member free to move radially about a limit of adifference between said inner diameter of said closure member and saidouter diameter of said guide element, said closure member eliminatingnoise emanating from said fluid valve.